Today on A Moment of Science - the cuckoo catfish.
The cuckoo catfish actually got its nickname because, like the cuckoo bird, it is a brood parasite. That means they trick the parents of other fish species into taking care of their eggs and young for them.
The cuckoo catfish parasitizes African freshwater fish called cichlids. Some cichlids have quite elaborate parental care compared to other fish. As soon as they lay their eggs, the female cichlids scoop them up into their mouths and incubate them until they hatch. The catfish can then smell the spawning cichlids and zooms into the cichlid nest, gobbling up a mouthful of their eggs while simultaneously laying its own eggs.
The catfish eggs have evolved to look just like the cichlid eggs. The mother cichlid can't tell which are hers and which are the catfish's, so she is forced to scoop them all up. And that's not even the end of it! The catfish eggs have also evolved to hatch earlier than the cichlid eggs. The newly hatched catfish quickly eat up any cichlid eggs. While the parasitism is clearly bad for the host cichlids, it's a great deal for the baby catfish. They get protection from the dutiful cichlid parents and also an easy meal upon hatching.
This strategy allows catfish to be more productive. By freeing themselves from the burden of tending their own brood, the catfish can breed again sooner, so they can produce many more offspring than they could have otherwise.